Re: [PATCH v2 0/1] Encapsulate the populate and alloc as one atomic

Mike Rapoport
2026-03-18T14:31:00Z

Hi Hubert,

On Tue, Mar 17, 2026 at 12:50:19PM +0000, Hubert Mazur wrote:
> Hello,
> thanks for the review of the v1 patchset. I tried to make v2 diff as
> small as possible and without a modification of the core logic.
>
> When a block of memory is requested from the execmem manager the
> free_areas tree is traversed to find area of given size. If it is not
> found then a new fragment, aligned to a PAGE_SIZE, is allocated and
> added to free_areas. Afterwards, the free_areas tree is being traversed
> again to fullfil the request.
>
> The above operations of allocation and tree traversal are not atomic
> hence another request may consume this newly allocated memory
> block dedicated to the original request. As a result - the first
> request fails to get the memory. Such occurence can be spotted on
> evices running the 6.18 kernel during the paralell modules loading.

typo: devices

In general, a single patch does not require cover letter, but the details
about why the patch is needed should be a part of the commit message.

> Regards
> Hubert
>
> Changes in v2:
> The __execmem_cache_alloc_locked function (lockless version of
> __execmem_cache_alloc) is introduced and called after
> execmem_cache_add_locked from the __execmem_cache_populate_alloc
> function (renamed from execmem_cache_populate). Both calls are
> guarded now with a single mutex.
>
> Changes in v1:
> Allocate new memory fragment and assign it directly to the busy_areas
> inside execmem_cache_populate function.
>
> Link to v1:
> https://lore.kernel.org/all/20260312131438.361746-1-hmazur@google.com/T/#t
>
> Hubert Mazur (1):
> mm/execmem: Make the populate and alloc atomic
>
> mm/execmem.c | 61 +++++++++++++++++++++++++++++-----------------------
> 1 file changed, 34 insertions(+), 27 deletions(-)
>
> --
> 2.53.0.851.ga537e3e6e9-goog
>

--
Sincerely yours,
Mike.